The present disclosure relates to spark plugs and more particularly, to spark plugs having a copper core.
Conventional spark plugs have primarily two functions in an internal combustion engine. The first is to efficiently ignite the fuel/air mixture and the second is to remove the heat out of the combustion chamber. A sufficient amount of voltage must be supplied by the ignition system to cause a spark to jump across the spark plug gap, creating an electrical performance. Additionally, the temperature of the spark plug""s firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling of the spark plug.
A conventional spark plug typically includes a ceramic insulator body having a center electrode and an outer metal shell assembled around the insulator body having a side electrode (or side wire) that is bent in an L-shape. The side electrode cooperates with the center electrode to generate a spark therebetween when an electrical voltage is applied between the electrodes.
The side electrode is generally a composite electrode having a copper (Cu) (or copper alloy) core. In one conventional spark plug, the side electrode has been created from a copper alloy combined with chromium (Cr) and zirconia (Zr). However, the Cu, Cr, and Zr are difficult to disperse uniformly. Additionally, the zirconia is a poor electrical and thermal conductor and it interferes with the strong Cuxe2x80x94Cr bonding. As a result, area of high concentrations of zirconia greatly decrease the electrical conductivity, the thermal conductivity and the strength of the alloy. Also, areas of low concentration of zirconia do not sufficiently restrict grain growth.
What is needed in the art is composition for the side electrode that sufficiently conducts electricity and is durable.
The deficiencies of the above-discussed prior art are overcome or alleviated by the spark plug copper alloy. A spark plug electrode, based upon the total weight of the electrode, is disclosed. The spark plug electrode comprises about 83 wt. % to about 96.8 wt. % copper, about 2.0 wt. % to about 9.0 wt. % chromium, and about 0.2 wt. % to about 8.0 wt. % niobium.
A spark plug is also disclosed. The spark plug comprises a shell disposed in contact with an insulator body. A center electrode is disposed at a lower end of the insulator body. A side electrode is also disposed at a lower end of the shell. This side electrode is coaxially aligned with the center electrode. At least one of the center electrode and the side electrode comprises a core composition of about 83 wt. % to about 96.8 wt. % copper, about 3.0 wt. % to about 9.0 wt. % chromium and about 0.2% to about 8.0% niobium, based upon the total weight of the composition. A resistor section is also disposed in electrical communication with the center electrode.